Sesko came off the bench to deny West Ham a vital 3 points in their hunt to avoid relegation, as his 96th-minute goal earned a 1-1 draw for United away at the London Stadium.
After coming up with the winner against Fulham two games ago, Sesko is gaining a reputation as a saviour for the Red Devils who still remain in the top 4.
Sesko is yet to start a match under interim boss Michael Carrick, and has struggled to impress since signing for the side in the summer.
Speaking after the game, Lammens has heaped praise on the 22-year-old, who has just 6 Premier League goals in 22 appearances.
“Honestly, he has been like this the whole season, even if he’s starting or not starting.
“He knows how important he is for us, even when he’s not starting, like today and against Fulham.
“Because in the end, when we need a goal, we can always count on him. So that’s why he was important today.
“He did his job well, but I’m sure if he starts, he’ll also do his job. It’s nice to be able to count on him on both occasions.”
Sesko has continued to work hard behind the scenes despite his lack of minutes after his performances over the past few weeks, Carrick may finally start him against Everton in the Premier League on Monday, February 23rd.
"We are living for each other," Sesko said. "We are doing everything to win the games, to secure the Champions League spot because we believe that we have the team for it.
"We have the quality and yeah, we're going to fight towards it. Unfortunately, the game was like it was. We have to now look forward to the next game and try to win it."